EXHAUST GAS MEASURING INSTRUMENT

摘要

An exhaust gas measuring instrument has a miniature dilution tunnel (22) in which a part of exhaust gas in the exhaust pipe (15) of an engine is introduced through an extraction pipe (30) and diluted with air, a measuring means (33 and 36) which measures specific components in the exhaust gas diluted in the miniature dilution tunnel (22), a high response differential pressure type extracted gas flow meter (31 and 40) which measures the exhaust gas flow rate (Qs) in the extraction pipe (30), a high response differential pressure type bypassed gas flow meter (29 and 39) which measures the exhaust gas flow rate (Qb) in the exhaust pipe (15) and an arithmetic means (44) which calculates the flow rate dividing ratio R = Qb/Qs which is obtained by dividing the exhaust gas flow rate (Qb) by the exhaust gas flow rate (Qs). The exhaust gas measuring instrument further has a means by which the calibration coefficient (k) of the flow rate dividing ratio is obtained and a means which obtains the calibrated flow rate dividing ratio (k.R) by multiplying the flow rate dividing ratio by the calibration coefficient. The calibration coefficient (k) can be obtained by dividing a concentration dividing ratio (Rc) by the flow rate dividing ratio (R).